Electrical device



Jan. 10, 1939. R, o. GRISDALE 2,143,414

ELECTRICAL DEVIC E Filed Aug. 25, 1954 /NVENTOR By R. O. GR/SDALE 04am 7dana@ ATTORNEY Patented Jan. 10, 1939 UNITEDv STATES PATENT OFFICE l ELECTRICAL DEVICE Application August 25, 1934,v Serial No. 741,367

2 Claims.

This invention relates to electrical devices and, more particularly, to a method of mounting such devices and to the article produced by the method.

An object of this invention is to mount an electrical device and, more particularly, a resistance device having a non-ohmic characteristic, so that its electrical characteristics are not affected by wide variations in humidity, or by severe mechanical shocks.

i A feature of the invention comprises a method of mounting a resistance member, element or device having a non-ohmic characteristic, that comprises molding the device in an insulating material and, more particularly, a synthetic resin.

A further feature comprises, prior to the molding operation, impregnating the resistance member with a material selected from the group consisting of waxes. resins and asphaltic materials.

Another feature comprises an electrical device J having an element of non-ohmic resistance embedded in a body of insulating material and, more particularly, a body of synthetic resin.

Still another feature comprises such an electrical device in which the element is initially impregnated with a wax, a resin or an asphaltic material.

Other and further features will be evident from the general and detailed description which follows hereinafter. ,A

In accordance with this invention, a resistance body comprising a disc or discs of a non-ohmic resistance material containing silicon carbide, or a disc or discs of cuprous-oxide coated copper, is impregnated with a material selected from the group consisting of waxes, .resins and asphaltic materials, such as ceresin, carnauba wax, rosin, polymerized styrol, benzyl cellulose, cellulose acetate, natural or compounded asphalt, and, thereafter is molded in a block or body of an insulating material, preferably a synthetic resin, such as a phenol condensation product, vinyl resin, plicform, benzyl cellulose or polymerized styrol, in a suitable die. molded in the synthetic resin block, also, the only exposed portions thereof being projections or lugs to which electrical conductors may be connected.

A more complete understanding of this invention will be obtained from the detailed description which follows, taken in conjunction with the appended drawing, wherein: Fig. 1 is a plan view of an electrical device in accordance with this invention;

Fig. 2 is an enlarged, cross-sectional view of the device of Fig. 1 taken along the line 2-2 thereof;

The contact plates or discs are Fig. 3 is a plan view of another electrical device in accordance with this invention;

Fig. 4 is an enlarged side view of the device of Fig. 3, partly broken away and partly in section taken along the line 4-4 of Fig. 5; 5

Fig. 5 is a plan view of still another electrical device in accordance with this invention; and

Fig. 6 is an enlarged side view of the device of Fig. 5, partly broken and partly in section taken along the line 6-6 of Fig. 5. l0

The electrical device of Figs. 1 and 2, generally designated I0, comprises a resistance device comprising superposed discs, plates, elements or members I I, preferably of a material having a nonohmic or non-linear voltage-current characteris- 15 tic, for instance, a material containing approximately 59% silicon carbide, approximately 39% clay, and approximately 2% graphite. Each member II is provided on its outer surface with contact layers I2, preferably of tin, formed there- 20 on, for instance, by Schoop-spraying. Contact discs, plates or members I3, which may be of brass and comprise a circular portion I4 of about the size of the members II, and a radially extending, integral Ilug or terminal projection I5, 25 engage the contact layers of the members Il, one contact member being interposed between the discs and the others engaging with the outer contact layers on themembers Il. The members II and I3 are molded in a suitable die in a 30 block or body I 6 of insulating material, preferably a synthetic resin, such as a phenol condensation product, vinyl resin, plioform, benzyl cellulose, or polymerized styrol, the extremities I'I, only, of the members I3 projecting from the 35 body I6. As a step preliminary to molding the vdiscs into the insulating body, it has been found desirable to impregnate the resistance members with a material selected from the group consisting of waxes, resins and asphaltic materials, such 40 as ceresin, carnauba Wax, rosin, polymerized styrol, benzyl cellulose, cellulose acetate, natural or compounded asphalt.

The electrical device of Figs. 3 and 4 comprises a full-wave, dry rectifier of the copper-cuprous 45 oxide type, designated generaly, 20. It comprises ,Y a unitary assembly 2I, comprising a supporting member or bolt 22 engaged at its threaded end 23 by a clamping member or nut 24. Clamped between the nut 24 and the bolt head 25 are a 50 pair of end plates 26, for instance, of steel; a pair of insulating washers 21, for instance, of phenol fiber; a plurality of copper discs or plates 28, each having a thin layer 29 of cuprous oxide integrally formed thereon by suitable heat treattin-coated lead; a plurality of terminal plates 3l,

for instance, of brass, each of which has a radially extending lug or projection 32; and a connector strap 33; the discs or plates 28, 36, 3l being in= sulated from the bolt by a tubular member 34 of phenol ber. The assembly 2l is molded, in a suitable die, in a block or body 35 of insulating material, preferably a synthetic resin such as is `mentioned hereinabove with reference to the def vice of Figs'. l and 2. The extremities 33, only, of the lugs 34 project outside of the block 35 and are adapted to have conductors 3l secured thereto, for instance, by solder.

The electrical device of Figs. 5 and 6 comprises a full-wave, dry rectifier of the copper-cuprous oxide type, designated generally, 40. It cornprises a plurality of alternately disposed superposed terminalplates 4l, for instance, of brass, each having a circular portion l2 and a radially extending lug or projection 43, and copper plates, discs, or members 44, each having a portion l5 of copper having a relatively thin layer 56 of cuprous oxide formed integrally thereon by suitable heat treatment, and a. relatively thin layer 41 of reduced copper formed integrally on the layer 46; a connector strap or member 48; and a body 43 of insulating material into which the members 4l, 44, 48 are molded in a suitable die. This insulating material is preferably the same as that embodied in the devices of Figs. 1-4. The extremities 5G, only, of the terminal lugs 43 are outside of the body 49. Asis well known, coppercuprous oxide rectier elements, such as lll, do not need to be mounted under pressure as in the case of the elements 28 of the device of Figs. 3 and 4.

Mounting electrical devices in the manner described hereinabove, produces a device whose electrical characteristics are not aiected by `wide ltier elements 44, protection variations in humidity, or by severe mechanical shock. With reference particularly to the recis aiorded, also, against atmospheric and other influences tending vto cause corrosion of the reduced copper layer,

which corrosion would result in a decrease in the rectication ratio as a result of an increased resistance in the forward or current passing direction of the element. In the case of the elements 28 of the device of Figs. 3 and 4, the oxide layers are protected, also, from inuences tending to cause an increase in the resistance of the element in its forward or current passing direction with a resultant decrease in rectication ratio. An

improved and more stable resistance device capable of effective use as an acoustic shock suppressor, electrical current rectifier, or the like, is thereby made available.

While this invention has been disclosed with reference to several'speciflc structures, it will be understood that various modifications therein may be made without departing from the invention, the scope of which is to be considered as limited only by the appended claims.

What is claimed is:

1. A resistance element of silicon carbide, clay and graphite, in the apprordmate proportions respectively of 59, 39 and 2 percent, that has been impregnated with a material selected from the group consisting of waxes, resins, and asphaltic materials, said element being molded in an in-l sulating material.

2. An electrical device comprising a plurality of discs of a material comprising silicon carbide, clay and graphite and each impregnated with a material selected from the group consisting of waxes, resins and asphaltic materials, and contact discs in engagement with said rst mentioned discs, said discs being enclosed and molded in an insulating material.

' RICHARD O. GRISDALE. 

